Upper limit on the coronal cosmic ray energy budget in Seyfert galaxies.

This article focuses on constraining the cosmic ray (CR) energy budget in the coronae of Seyfert galaxies, a class of active galactic nuclei (AGNs) without strong jet activity, in light of high-energy neutrino detections reported by the IceCube Collaboration. By incorporating accretion dynamics and observed coronal properties, the study establishes a stringent upper bound on the coronal CR power, which implies that the expected neutrino flux from sources like NGC 1068 is about an order of magnitude lower than IceCube observations. This discrepancy suggests that additional neutrino production mechanisms or sources beyond the corona may be involved, or that background contamination could affect the signals. The paper also discusses the implications of plasma magnetization (plasma beta, β) on particle acceleration processes, favoring diffusive shock acceleration in high-β, weakly magnetized coronae typical of radio-quiet Seyferts, while noting challenges for stochastic acceleration and magnetic reconnection flares. Further theoretical and observational studies are recommended to resolve these tensions and better understand neutrino emission from Seyfert galaxies.